Switch, Firewall, and DHCP Question

Looking for some guidance on the general direction I need to go.  I have a Fortinet (61E) I've been using for over a year.  Recently acquired a FortiSwitch 108D-POE.  I have the switch connected to the Fortinet and can manage it through the webUI.  I have a separate VLAN for the switch and the Fortinet.  Fortinet default software switch is configured as a DHCP server (192.168.5.1/24) and the FortiSwitch has a separate VLAN (vsw.internal1) also configured as a DHCP server (192.168.3.1/24).  

What I would like to do is have a VLAN on the switch for ports 1-5 on the same VLAN as the Fortinet, then have ports 6-8 on a separate VLAN.  

I can't seem to figure out how to make this happen.  I've tried various combinations of DHCP Relay and trying to add a VLAN with the same IP range. Nothing seems to work.  Any suggestions would be greatly appreciated.